Research And Application Based On Inorganic Nanomaterials And Designed Functional DNA Nanostructure

Development of nanotechnology, promote breakthroughs in a number of disciplines andfields, especially in materials, biology, medicine, chemistry, electronics, optics and otherdisciplines. Nanotechnology promote the cross and integration between several disciplines, so asto provide new methods and opportunities to solve the problems. Based on this, the paper carriedout the research and application based on nanomaterials. These materials include goldnanoparticles (zero-dimension), carbon nanotubes (one-dimension), graphene oxide (twodimension), DNA nanostructures (three-dimension). This paper involves the research aboutinteraction of biological molecules with inorganic nano-materials, nano-sensors based onfunctional nano-materials, design and application of DNA nanostructures. The main findings areas follows:(1) In this section, we report a conceptually new strategy to prepare conjugates of DNA andgold nanoparticles (AuNPs). Based on our discovery that poly-adenine (polyA) can bind to thehighly curved surface of AuNPs with extraordinarily high affinity, we designed a diblockoligonucleotide with the anchoring block (ployA) and the recognition block (DNA sequence forrecognition) for conjugation with AuNPs. The significance of this type of diblockoligonucleotide-based conjugation strategy is described as follows:①Diblock oligonucleotidesare natural sequences that are essentially free of any modification.②PolyA effectively blocknon-specific DNA-gold binding.③Our new strategy provides favorable hybridization ability inboth kinetics and thermodynamics.(2) We discussed the different behavior of different DNA structure on GO surface. In thisstudy, we researched on different DNA absorption state on the graphene surface, such as ssDNA,ssDNA including piece dsDNA, RCA products, DNA hairpins, long dsDNA with ssDNA distalend and3D DNA structure. Based on fluorescence assay of fluorescence restored, RCA systemand HCR system, it was proved that all of the nucleobases laid nearly flat on the GO surface andssDNA were stably adsorbed by the GO. And the fluorophores in double strand fragments couldleave the GO surface, but the surplus single strand DNA would be stably adsorbed on GOsurface even if those took the small percentage of the long DNA strand.(3) we have demonstrated that the adsorption of CPEs on GO was related to the molecularstructure of CPEs and the functional groups present at the surface of GO. Based on thesuperquenching of cationic CPEs by GO and different absorption mechanism of ssDNA and dsDNA on GO, we have developed a sensitive homogeneous sensor for DNA detection anddemonstrated its improved S/N ratio and high specificity.(4) In this work,three water soluble nanomaterials,0D AuNPs,1D SWNTs, and2D GO,and their characterized interaction with DNA were investingated detailed for well understandingtheir characters and designing sensing stratigies. The fluorescence quenching behavior of NMs,the performance of three NMs-based sensors, and the NMs-DNA interaction were well studiedhere. The highest differentiation of ssDNA and dsDNA were achieved by employingnanomaterials. Consequently, the GO-based sensor exhibited the best sensitivity (LOD:0.2nM),while1nM of LOD for SWNTs group and2nM for AuNPs group were presented. Worthy ofnoting, GO-and SWNTs-based sensors exhibited excellent discrimination of single mismatchbase pairs from perfect matched sequences. More importantly, the related mechanisms werecarefully analyzed through investigating the usage of NMs and the concentration of NaCl.(5) In this section, we synthesised the3-helix and6-helix DNA structure with high yield,and characterized and determined its size and integrity. Meanwhile, we have studied the stabilityand resistance degradation of6-helix DNA structure. Data show that the stability and resistancedegradation of6-helix DNA structure were very well. By optimizing the structure of the chains,we achieved the high efficiency switching of6-helix structure. Base on these, we havesuccessfully achieved the controllable switching of6-helix structure in vivo. In addition, we triedto take CpG drug molecules into the cells with setting its in the interior of6-helix DNA structure.However, experimental data shown that3-helix structure and the6-helix structure itself hadstrong immune stimulating activity, which covered up the stimulating activity of CpG molecules.And its mechanism of this action has to be studied in the future.